Valve control for a vacuum chamber



. Oct. 6, 1959 R. s. RANDALL VALVE CONTROL FOR A VACUUM CHAMBER FiledApril 18. 1955 United States. Patent VALVE CONTROL FOR A VACUUMCHAIVIBER Ralph S. Randall, San Francisco, Calif.

Application April 18, 1955, Serial No. 502,077

2 Claims. (Cl. 137-565) The present invention relates to improvements ina valve control for a vacuum chamber, and has particular reference to avalve control used in connection with the Vacuum Bag Sealing Machinedescribed in my co-pending application, Serial No. 486,797, filedFebruary 8,

1955, now Patent No. 2,833,096, grantedMay 6, 1958. In this machine, thebags are sealed in a vacuum chamber and it becomes necessary, in theoperation of the machine, to open the chamber for positioning the bagstherein, to close the chamber, to apply the vacuum, to perform thesealing operation, to relieve the vacuum, and to re-open the chamber forremoval of the finished bags and for the introduction of new bags.

In my present invention, it is proposed to provide a suitable valve forapplying and relieving the vacuum.

It is further proposed to provide a valve of the character describedwhich is operated by the vacuum already available which considerablyreduces the cost of the machine as compared with other methodsheretofore used for similar purposes.

It is still further proposed to use a vacuum' tank for periodicallyapplying vacuum to the valve for operating the same and to provide anarrangement whereby the vacuum in the tank is maintained automatically,as an incident to the operation of the machine.

Further objects and advantages of my invention will be apparent as thespecification proceeds, and the new and useful features of my valvecontrol for a vacuum chamber will be fully defined in the claimsattached hereto.

The preferred form of my invention is illustrated in the accompanyingdrawing, forming part of this application, which shows a side view of myvalve control, portions being shown in section.

While I have shown only the preferred form of the invention, it shouldbe understood that various changes or modifications may be made withinthe scope of the claims hereto attached, without departing from thespirit of the invention.

Referring to the drawing in detail, my invention comprises in itsprincipal features, a control valve 1, a vacuum tank 2, a solenoid valve3 and connecting conduits to be described as the specificationcontinues.

The control valve comprises a housing 4 including a generallycylindrical, vertical section 5 and a transverse head 6 threadedthereon, as at 7. The head and the upper portion of the vertical sectionform an upper valve chamber divided by a diaphragm into an upper portion8 and a lower portion 9, the diaphragm presenting an open horizontalvalve seat 10 between the two chambers.

The upper edge of the vertical section 5 of the housing forms a secondopen valve seat, which is mounted opposite the first valve seat and inspaced relation thereto.

The head 6 is in the form of a T, and has two conduits 12 and 13projecting therefrom, the conduit 12 leading to a vacuum pump, notshown, and the conduit 13 leading to the vacuum chamber (not shown).

Below the valve seat 11, the housing is formed with a number of ports 14leading to the atmosphere.

' pulling the latter and the plunger 20 and the valve 21' Below theports 14, the diameter of the housing is reduced to present a waist 15,and below the waist it expands again to present a lower piston chamber16, which has a bottom head 17 screwed thereon, as at 18. The bottomhead is stepped down in diameter to receive the fitting 19. Y

A plunger 20 is slidable vertically in the waist of the housing, and hasupper and lower ends extending intov the upper and lower chambers,respectively.

The upper end of the plunger carries a disc valve 21,

which is movable between the upper and lower valve. seats 10 and 11,respectively, and is provided with upper. and lower washers adapted toseal either the lower or.

The lower end of. the plunger carries a piston 22,

including a washer 22'rnovable in the chamber 16 and bearing against thewall thereof, the washer having atapered rimand being anchored to theplunger by means of two discs 23 and 24 urged upon the lower end of theplunger by a bolt 25 screwed into the plunger. A vent 25' is provided inthe chamber 16 above the piston.

Upward pressure is applied to the plunger 20 by means of a spring 26bearingagainst a shoulder 27 in the head 17 and against the bottom disc24, so that normally the valve 21 is in its uppermost position, with itsupper washer bearing, against the seat 10, which means that the passagebetween the conduits l2 and 13, leading to the pump and vacuum chamber,respectively, is closed,

while the passagefbetween the ports 14 and the vacuum chamber is open,allowing air to enter the vacuum chamber. v

The vacuum tank 2 is connected to the fitting 19 at the bottom of thevalve housing by means of the conduit 28, causing suction to be appliedto the piston 22 and downward against the tension of the spring 26, whenthe conduit is open.

This causes the valve to open the valve seat 10 and close the valve seat11, establishing communication between conduits 12 and 13 and closingthe passage between the ports 14 and the suction chamber.

The conduit 28 is controlled by the solenoid valve 3, which is ofconventional construction, and made to open the conduit in one positionto apply suction to the piston 22, and to open the valve housing side ofthe conduit to the atmosphere in the other position, so as to relievethe suction, as indicated by the arrows.

Vacuum is maintained in the tank 2 through the conduit 29, whichconnects the upper part of the tank with the upper portion 8 of theupper chamber in the valve housing, the portion 8 being in constantcommunication with the conduit 12 leading to the vacuum pump, so thatthe tank is subjected to the suction of the pump at all times.

However, when the valve seat 10 is opened and the pump is made to drawon the suction chamber, the pressure in the conduit 29 increasesmomentarily, and since a high vacuum is desired for the tank, I providea check valve 30 in the conduit 29 adjacent the tank.

The check valve 30 allows air to be sucked from the tank through theconduit 29, but automatically prevents a reverse flow of the air incasethe pressure in the conduit 29 is higher than that in the tank.

In operation:

The valve at 10 is normally closed, as shown, under the pressure of thespring 26, so that there is no comrnunication between the vacuum pump(conduit 12), and the suction chamber (conduit 13). On the other hand,air from the atmosphere is free to enter the suction chamber throughports 14 and the conduit 13.

At the same time, the suction of the pump draws on Patented Oct. 6, 9"

the atmosphere to communicate with the space underneath the piston 22,so as to relieve the vacuum at that point. This condition prevailsduring the loading period of the vacuum bag sealing machine.

After the machine has been loaded and the operator has closed the vacuumchamber, he operates the solenoid valve 3 to open the conduit 28 andclose the latter against the atmosphere. The vacuum in the tank thendraws on the bottom face of the piston 22, pulling the plunger assemblydownward and opening the upper valve at 10, While closing the valve at11.

The closing of the valve at 11 blocks the flow of air from theatmosphere to the vacuum chamber, while the opening at 10 places thevacuum chamber in direct communication with the vacuum pump forevacuating the vacuum chamber.

If, at this time, the pressure in the conduit 29 increases momentarily,the vacuum in the tank 2 will remain unaffected on account of the checkvalve 30.

After the vacuum chamber has been evacuated and the bags have beensealed, the solenoid valve is again actuated, either manually orautomatically by suitable timing means, to close the conduit 28 againstthe tank 2 and to open it to the atmosphere, whereby the vacuumunderneath piston 22 is relieved and the spring is allowed to return thevalve 21 to its normal position, as shown, to relieve the vacuum in thechamber.

I claim:

1. In combination with a vacuum chamber, a tank mounted outside thechamber, a vacuum pump having connection with the vacuum chamber, avalve housing in said connection having a diaphragm dividing the sameinto an upper compartment and a lower compartment, with a valve seat insaid diaphragm, the upper compartment being connected to the pump andhaving unrestrict ed connection with the tank to maintain a vacuum insaid tank, the lower compartment being connected to the vacuum chamberand to the atmosphere, a second valve 4 a seat between the lowercompartmentand the atmosphere connection and arranged opposite the firstvalve seat, a

valve in'said lower compartment operable for closing either of the valveseats, spring means urging the valve upon the first seat, a conduitconnecting the tank and the valve housing and adapted to apply suctionto the valve for opening the first valve seat and closing the secondvalve seat, and a control element in the latter conduit adapted torender the suction means active or inactive, the connection between theupper compartment and the tank having a check valve therein operative toprevent air pumped from the vacuum chamber from entering the tank.

2. In combination with a vacuum chamber, a tank mounted outside thechamber, a vacuum pump, a valved connection between the pump and thechamber, means providing a passageway connecting said tank with thevacuum pump side of said valved connection for maintaining a vacuum insaid tank, spring means for normally closing the valve, a conduitconnection between the tank and the valve having a control elementoperable for applying suction to said valve for opening the same, and acheck valve interposed in said passageway and operative to preventairfrom entering said tank from said valved connection.

References Cited in the file of this patent UNITED STATES PATENTS

